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Leachia Lesueur 1821

Richard E. Young and Katharina M. Mangold (1922-2003)
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Six of the 14 nominal species of Leachia are considered valid by Voss, et al. (1992). These authors suggest that 11 species exist in the genus, 5 of which are undescribed.

Containing group: Cranchiinae

Introduction

Species of Leachia are easily recognized by the straight cartilagenous, tubercular strip on the mantle that arises from each point of funnel-mantle fusion, the slender, tapering mantle and the terminal fins with a combined oval shape.

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Figure. Ventrolateral view of the antrior region of Leachia dislocata showing a transparent, cartilagenous strip bearing tubercules (arrow). Tubercules can be difficult to see because of their transparency. Photograph by R. Seapy.

Leachia species, however, are not easily recognized. Many names exist in the literature and most have poor descriptions associated with them and are based on paralarvae. At present, geographical location is one of the most important characteristics used in identification. The type localities of the named species are:

Atlantic Ocean
Indian Ocean
Pacific Ocean

Brief diagnosis:

A cranchiin...

Characteristics

  1. Tentacles
    1. Median suckers of tentacular club greatly enlarged.**
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      Figure. Oral view of the tentacular club of Leachia dislocata, 136 mm ML. Drawing from Young (1972).

  2. Head
    1. Eyes stalked in paralarvae.


    2. Beaks: Descriptions of L. danae beaks can be found here: Lower beak; upper beak.

  3. Funnel
    1. Funnel valve absent.
    2. Funnel organ: dorsal pad U-shaped with 3-7 papillae.

  4. Mantle
    1. Single tuberculate cartilagenous strip on mantle originates at each funnel-mantle fusion.*

  5. Fins
    1. Fins barely unite posterior to gladius (transversely elliptical in combined outline).

  6. Photophores
    1. Each eye with 5-21 oval photophores depending on species.
    2. Photophores on tips of arms III in mature or nearly mature females.
*Unique feature in family.
**Unique feature in family where suckers unmodified (not hooks or hook-like suckers)

Comments

This is the only genus in the subfamily Cranchiinae with paralarvae that have stalked eyes. Characteristics are from Voss (1980).

Comparison of species

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Figure. Comparison of the structure of the mantle tubercular strips among five of the species. A - Leachia lemur, north Sargasso Sea, 42 mm mL. B - Leachia atlantica, subtropical North Atlantic, 54 mm ML. C - Leachia dislocata, off California, 34 mm ML. D - Leachia danae, eastern tropical Pacific, 53 mm ML. E - Leachia pacifica, off Hawaii, 41 mm ML. Drawings from Voss, et al. (1992, p. 191).

Life History

The paralarvae of the genus have a very distinctive appearance. A paralarva has a very long, slender brachial pillar and a pointed tip to the gladius. Paralarvae of Leachia were originally placed in the genus Pyrgopsis and are now often referred to as pyrgopsis paralarvae.

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Figure. Dorsal and ventral views of paralarval L. pacifica, 7.9 mm ML, Hawaiian waters, original.

Distribution

Vertical distribution

Off Hawaii, L. pacifica has a peculiar vertical distribution pattern which may prove to be common within the genus. Small squid are found in near-surface waters. As sexual maturity approaches, the squid undergoes an abrupt ontogenetic descent. At depths greater than 1000 m males and females become mature. Large photophores develop on the tips of the third arms of females and these are, presumably, used to attract males at great depths where the risk of predation is low.

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Figure. Vertical distribution chart of L. pacifica, Hawaiian waters. Captures were made with both open and opening/closing trawls. Bars - Fishing depth-range of opening/closing trawl. Circle - Modal fishing depth for either trawl. Blue color - Night captures. Yellow color - Day captures. Chart modified from Young (1978).

References

Voss, N. A. 1980. A generic revision of the Cranchiidae (Cephalopoda; Oegopsida). Bull. Mar. Sci. 30: 365-412.

Voss N. A., S. J. Stephen and Zh. Dong 1992. Family Cranchiidae Prosch, 1849. Smithson. Contr. Zool., 513: 187-210.

Young, R. E. 1972. The systematics and areal distribution of pelagic cephalopods from the seas off Southern California. Smithson. Contr. Zool. 97:1-159.

Young, R. E. 1978. Vertical distribution and photosensitive vesicles of pelagic cephalopods from Hawaiian waters. Fish. Bull. 76: 583-615.

Title Illustrations
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Scientific Name Leachia dislocata
Location Off Southern California
Specimen Condition Live Specimen
View Side
Size 100 mm ML (estimate)
Image Use creative commons This media file is licensed under the Creative Commons Attribution-NonCommercial License - Version 3.0.
Copyright ©
Scientific Name Leachia dislocata
Reference from Young, R. E. 1972. The systematics and areal distribution of pelagic cephalopods from the seas off Southern California. Smithson. Contr. Zool. 97:1-159.
View Ventral
Size 110 mm ML
Image Use creative commons This media file is licensed under the Creative Commons Attribution-NonCommercial License - Version 3.0.
Copyright ©
About This Page


University of Hawaii, Honolulu, HI, USA

Katharina M. Mangold (1922-2003)
Laboratoire Arago, Banyuls-Sur-Mer, France

Page: Tree of Life Leachia Lesueur 1821. Authored by Richard E. Young and Katharina M. Mangold (1922-2003). The TEXT of this page is licensed under the Creative Commons Attribution-NonCommercial License - Version 3.0. Note that images and other media featured on this page are each governed by their own license, and they may or may not be available for reuse. Click on an image or a media link to access the media data window, which provides the relevant licensing information. For the general terms and conditions of ToL material reuse and redistribution, please see the Tree of Life Copyright Policies.

Citing this page:

Young, Richard E. and Katharina M. Mangold (1922-2003). 2007. Leachia Lesueur 1821. Version 30 June 2007 (under construction). http://tolweb.org/Leachia/19544/2007.06.30 in The Tree of Life Web Project, http://tolweb.org/

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